Lead for pencils, color pencils, copying pencils, or the like and process for manufacturing the same



Patented Mar. 7,l 1939 ,UNITI-:o sTATss LEAD FOB. PENCILS, COIR PAENCILS, COPY- ING PENCILS, R THE LIKE AND PROCESS FOR MANUFACTURING THE SAME Richard Ziiekert, Bohmisch-Bndweis, Czechoslovakia, assignor to the firm Koh-i-noor tui-kama L. C. Hardtmuth, Ces. Budejovice,

' Czechoslovakia Application May20, 1937, Serial No. 143,84il In Germany May 30, 1936 4 Claims.

This invention relates to a lead for black lead. colored and copying pencils and the like with articially produced hollow space. These hollow spaces in the lead are, according to the invention,

,1 constructed as passages extending parallel to the axis of the lead, and preferably of such diameter that capillary effects are produced.

Such a lead may, for example be connected at its rear end with a container for a writing liquid y) such as ink which when the lead is being used for writing flows through the passages on tothe paper and completes the line drawn with the pencil. In this manner the two fundamentally different proceedings of writing witha pencil and of writ- 5 ing with a nib are combined. A stroke drawn with a pencil alone cannot completely color the paper, as the lead particles adhere only on the projecting cellulosefibres ot the paper and uncolored paper portions remain between them, this being particularly visible, if pencil strokes are copied by hellographic calking. Such uncolored paper islands are, however, attained by the writing liquid contained in the capillary passages of a lead according to the invention, so that it is thus possible to produce a drawing instrument of particularly great usefulness.

The lead with capillary passages presents further the possibility to produce a first-quality hectographic-ink stylus, which has not been possible up to the present, because the number of hecto- A graphic copies which can be made depends on the glycerine-percentage of the lead, which is how*- ever, very limited for technical reasons in the compact lead, these reasons being no longer valid for the lead having capillary passages according to the invention.

The manufacturing of a lead with artificial hollow spaces may be effected in various man` so the lead may be produced in two different manners. The one manner consists in providing in the commonly used mass for leads parallelly extending bores and to fill these bores with a substance adapted to easily develop gas and of 'additions which' render this substance plastic up known manner, to strings of square or rectangu- 10 lar cross-section, and these strings .mixed to a compound mass-body showing in cross-section the 1 two masses mixed, checquered in squares, whereupon the compound mass-body is pressed to form a lead and this lead subsequently treated for gas- 15 development.

The advantages of the invention are present in some cases of application even then, if the dimensions of thehollow spaces become so great that the capillary eilects are no longer prepon- 20 derant.

A favorable combination for the insert according to the invention in bodies of lead-mass is amongst others as follows:-

900 grs. naphthalene in the form of avery ne 25 powder,

grs. calcium stearate in the form of finest powder,

25 grs. coloresin, (methyl cellulose) swelled in 400 grs. water. 3,0

Two embodiments of the invention are illustrated, by way of example, in the accompanying drawing, in which:-

Fig. l shows on an enlarged scale a cross section through a lead. 35

Fig. 2 is a longitudinal section on line II-II of Fig. l. l e

Fig. 3 shows in longitudinal section the prof duction of a lead in an ordinary lead press.

Fig. 4 is a cross section through the lead mass 40 taken on line IV- -IV of Fig. 3.

Fig. 5 shows on a slightly larger scale the pressed lead in cross section on line V-V of Fig. 3.

Fig. 6 shows in longitudinal section the modi- 45 ecl manner of production of a lead in an ordinary lead press.

Fig. 7 is a cross section through the lead mass taken on line VII-VII of Fig. 6.

Fig. 3 shows on a slightly enlarged scale the 50 pressed lead in cross-section on line VIII--VIII cf'Fig. 6. l

The lead I in Figs. l and 2 has a central cap- -illary passage 2 and eight capillary passages 3 passage. In producing this lead by the method illustrated in Figs. 3 to 5, an ordinary lead mass is shaped in the i'orm of a cylinder 4 and provided with passages 5 which are illled with a second mass composed of a substance which easily gives off gas with suitable admixtures for rendering it plastic (Fig. 4). The cylinder l composed 0i' two different masses is placed in a cylindrical press cylinder and subjected to pressure by 'a piston I which forces the mass through a mouthpiece 9 in compressed state in the form of a lead 8 (Fig. 3). Fig. 5 shows the cross sectionoi the lead 8 whose passages or bores have become of capillary size owing to the reduction of the crosssectional area, but are still filled with the mass which easily liberates gas. The compressed lead 8 is now subjected to a treatment for liberating gas whereby the finished lead with hollow cap-k illary passages is produced.

Figs. 6 to 8 show a second manner for producing such a capillary lead. A number of strings I0 of square cross-section is produced from the ordinary lead composition. A number of strings I I of exactly the same cross sectional shape is produced from a second composition capable of giving oil? gas. These strings I0 and Il are then united to form a composite string as shown in Fig. 7, each string` I I being surrounded by strings III- and consequently separated from the next string 4I I. This thick composite string is now inserted in a lead press I2 of square cross-section, in which it is forced through a mouthpiece` tov form a lead I4, as in the method illustrated in Figs. 3 to 6. If the mouthpiece is of circular cross-section a round lead is produced and the strings II of substance giving off gas, for example four in number, embedded in the composite string are deformed to more or less circular cross section (see Fig. 8). The compressed lead is then subjected to a gas liberating treatment and is thereafter ready for use.

continuous passages extending parallel to the axis of the lead, consisting in using a common lead mass having parallel longitudinal strands of a second mass which consists of a granular substance easily developing gas and made plastic by convenient additions, in pressing the mixed mass to form the lead, and in iinally treating this lead in a suitable manner for causing the gasv development" 4. A process for the production of 'leads with continuous passages extending parallel to the axis of the lead, consisting in producing, besides a body of commonly used lead mass, a second body of a mixture consisting of a substance capable ci' developing gas and of additions adapted to render this substance plastic, in shaping these two 'kinds of bodies intoistrings of square crosssection, in uniting these strings to form a compound body in such a manner, that in the cross section of. the compound body the strings of the developing substance lie on the places desired for the parallel passages, in compressing the compound body to the proportions of a lead, and in submitting this lead to a treatment for developing gas.

RICHARD ZCKERT. 

